Walter Brattain, William Shockley and John Bardeen produced the first transistor in December 1947 at Bell Laboratories. It was not until the late 1950s, however, that transistors became sufficiently reliable and inexpensive to be used as switching elements in computer circuitry. Since they were smaller and used less power than vacuum tubes, transistors allowed for greater circuit density and decreased cooling and power requirements. Circuit boards, like those shown here, connected transistors and other components to form the basic building blocks of computers. By the early 1960s, almost all computers were made with transistors.